The effect of coprecipitation in some key spent fuel elements

This paper presents the results obtained from coprecipitation experiments of uranyl solutions in the presence of metallic iron and/or its alteration phases in synthetic bentonitic-granitic composition water. Experiments were done under oxidising conditions at room temperature. The pH range covered was 7.4 -8.8. Changes in the uranium concentrations and the characterisation of the secondary phases formed in the experiments were done using XRD and SEM-EDS and are presented herein.Final uranium concentration values were in the range of 2·10 -5 -5·10 -4 mol (kg of H 2 O) -1 . In all cases, results from these experiments did not show evidence of a clear effect due to the presence of iron (metallic or previously corroded) on the uranium concentration. These data were similar to those obtained by coprecipitation in similar conditions but in absence of iron material.Boltwoodite was observed [K 2 (UO 2 ) 2 (SiO 3 ) 2 (OH) 2 ·3H 2 O] in iron surface materials and characterized in all experiments. Based on the experimental data obtained (uranium concentration in solution and bulk solid phase characterisation) we propose the following surface-mediated reaction: 2

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“…Aliquots of the aqueous suspension were taken at certain time intervals with a syringe for filtration [6,7]. No precipitation was observed.…”

Section: Precipitation Methodsmentioning

confidence: 99%

Coprecipitation Experiments Using Simulated Spent Fuel Solutions in the Presence of Metallic Iron in Synthetic Bentonitic-Granitic Water Under Oxidising Conditions

2004

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“…A titration process was performed in accordance with the established procedure [2][3][4]. NaOH (0.1 N) was used to adjust the pH to three different values (5.3, 7 and 9).…”

Section: Experimental Methodologymentioning

confidence: 99%

“…This paper describes the co-precipitation phenomena of dissolved spent fuel in different media [2][3][4], and focuses on the results obtained from precipitation and co-precipitation tests performed with U and Pu in a supersaturated solution of granitic-bentonitic groundwater. This scenario would take place after ≈10,000 years of disposal following contact between the groundwater and the spent fuel.…”

Section: Introductionmentioning

confidence: 99%

Radiolysis effects on U–Pu co-precipitation experiments in granitic–bentonitic groundwater under oxidizing and anoxic conditions

Quiñones

Iglesias

Esparza

2007

Journal of Alloys and Compounds

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Building Stakeholder Confidence by Reducing the Gulf between Experimental Data and Model Predictions in Assessments of Repository Performance

Hart

2004

MRS Proc.

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Confidence in the ability of repository systems to isolate high level wastes from the environment can be strengthened by placing greater reliance on robust designs for the repository system, and by using multiple lines of evidence to demonstrate that parameters, models and predictions developed for the repository are relevant. A particularly useful approach is to demonstrate that models and predictions incorporate processes that have been shown to be important in existing natural systems.

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The effect of coprecipitation in some key spent fuel elements

Cited by 4 publications

References 14 publications

Coprecipitation Experiments Using Simulated Spent Fuel Solutions in the Presence of Metallic Iron in Synthetic Bentonitic-Granitic Water Under Oxidising Conditions

Coprecipitation Experiments Using Simulated Spent Fuel Solutions in the Presence of Metallic Iron in Synthetic Bentonitic-Granitic Water Under Oxidising Conditions

Radiolysis effects on U–Pu co-precipitation experiments in granitic–bentonitic groundwater under oxidizing and anoxic conditions

Building Stakeholder Confidence by Reducing the Gulf between Experimental Data and Model Predictions in Assessments of Repository Performance

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